High-voltage switchgear systems, in particular gas-insulated high-voltage switchgear systems (GIS) are generally known and have been used for many years in the voltage range of about 7.2 kV to 800 kV. GIS systems are usually designed using modular techniques. System components such as busbars, isolating switches, circuit breakers, transducers, if necessary with cable sealing boxes and connecting elements, are in this case arranged as gas-tight encapsulated modules. Sulphur hexafluoride (SF6) is normally used as the insulating gas, but other gases are also used.
In such high-voltage switchgear systems, drives, which move electrical contacts, for example, in isolators, switches etc, are necessary in order to guarantee the proper operation of such a system. For this purpose, hydromechanical drives are used amongst others in order to carry out the movement of electrical contacts for different switching sequences. One of these switching sequences is so-called CO switching, which includes a closing with a subsequent re-opening of a switch. On the drive side, this switching sequence is brought about by an auxiliary switch, which normally has several contacts, which close or open depending on a drive position of the switch. In CO switching, the signal for the opening signal is already given when the switch closes; however the appropriate circuit remains interrupted due to the auxiliary switch until the drive has almost reached the closed position. However, for some switchgear systems, the time needed for the switching sequence by the drive controlled in this way is so small that the closed position is never reached and is overlaid by the opening operation in such a way that, all in all, the switch does not close properly.